In a process for manufacturing a semiconductor device including a large number of various semiconductor elements such as transistors, fine-line patterning techniques are essential to increase integration degree. In these days, the development of various lithographic techniques has been enthusiastically advanced for further finer patterns. One of issues in lithographic technology is improvement of photomask accuracy.
To improve the photomask accuracy, the interior of glass of a photomask is irradiated with a femtosecond laser to alter the quality of the glass, thereby correcting the dimension accuracy, position accuracy, and flatness of the photomask.